In a standard packing operation such as described in copending application Ser. No. 08/229,324, filed Apr. 18, 1994 and Ser. No. 08/233,233, filed Apr. 26, 1994 flattened cartons are erected by an apparatus and deposited in respective cells of a conveyor. The erected boxes are then moved past a packing machine that loads the contents into them and they are sealed and shipped out.
Such an operation, which for instance is used in a manufacturing operation, must be capable of accommodating cartons of different sizes so that, when a production line is switched, cartons of the appropriate size can be used. The erecting machine can be set to pick off and set up the differently sized cartons. German patent document 4,036,510 describes such a conveyor which has three chains each carrying a succession of abutments, with three abutments defining a seat or cell for receiving a single respective carton. The chains are parallel and pass over respective coaxial sprockets spaced axially apart on a common shaft. The sprockets of the two outer chains are axially fixed relative to each other while the sprocket of the center chain is mounted on a sleeve that is movable angularly on the shaft so that it can be angularly displaced and fixed, thereby adjusting the spacing between the center abutments and the flanking side abutments in the transport direction. A motor mounted on the rotating shaft effects the necessary adjustment.
Adjusting such a system is not simple. The motor, which must be energized through a system of commutator rings, is prone to failure. In addition the use of only three holders means that a carton can easily get canted in its holder, making it difficult or impossible to pack. What is more the relative adjustability is limited by how much the sleeve of the central sprocket can move angularly on the sprocket shaft, typically only 90.degree., so that very small or very large boxes cannot be accommodated.